UNIVERSITY  OF  CALIFORNIA      AGRICULTURAL   EXPERIMENT  STATION 

BENJ.    IDE    WHEELER,    President 

COLLEGE   OF  AGRICULTURE  thomas  fohsyth  hunt,  dean  ano  director 

__  _j,_  .    p-v  H.    E.     VAN     NORMAN,    Vice-Director    and    Dean 

"  tnlXLLt  Y  University    Farm    School 


CIRCULAR  No.  155 

September,  1916 


BOVINE   TUBERCULOSIS 

By  C.  M.  HARING 


In  view  of  recent  legislation  in  this  state  concerning  the  sale  of  dairy 
products,  which  becomes  effective  October  1,  1916,  it  has  been  deemed  advisable 
to  publish  some  fundamental  facts  concerning  bovine  tuberculosis.  (See  California 
Statutes,  1915,  p.  1478.)  This  station  has  no  responsibility  concerning  the  new  law. 
All  communications  concerning  it  should  be  addressed  to  the  State  Dairy  Bureau 
or  to  the  State  Veterinarian.     (See  note  bottom  p.  2.) 

Cattle  are  the  most  susceptible  of  all  animals  to  tuberculosis. 
Hogs  also  contract  the  disease  easily  when  fed  on  infected  milk 
or  when  running  in  fields  with  tuberculous  cattle.  Poultry  are  some- 
times affected  with  a  form  of  tuberculosis,  as  are  also  household  pets. 
In  fact,  there  is  no  kind  of  animal  that  will  not  develop  the  disease, 
although  horses  and  sheep  are  seldom  infected.  Tuberculosis  is  the 
most  serious,  infectious  disease  of  man.  The  bovine  type  of  bacillus 
rarely  causes  the  lung  form  of  the  disease  in  adult  human  beings, 
but  it  is  responsible  for  certain  types  of  tuberculosis  in  infancy  and 
childhood.  The  percentage  of  cases  of  the  bovine  type  occurring  among 
children  depends  on  local  conditions,  and  is  variously  estimated.  The 
maximum  found  in  any  locality  has  been  25  per  cent.  The  cause  of 
this  disease  in  children  is  infection  transmitted  through  raw  milk  and 
cream.  It  may  also  be  present  in  other  dairy  products,  such  as  butter, 
fresh  cheese,  skimmed  milk  and  buttermilk. 

THE   ECONOMIC   ASPECT   OF   BOVINE    TUBERCULOSIS 

The  losses  due  to  the  prevalence  of  this  disease  in  farm  animals 
are  not  as  apparent  as  they  are  important.  It  is  no  uncommon  thing 
for  a  veterinarian  to  find  70  or  80  per  cent  of  the  cows  in  a  herd 
diseased  without  much  loss  being  evident  to  the  owner.  Losses  from 
deaths  due  to  tuberculosis  seldom  become  serious  in  a  herd  until  the 
disease  has  spread  to  a  majority  of  the  animals.  Often  the  first  inti- 
mation that  anything  is  wrong  comes  to  the  owner  through  the  report 


from  the  abattoir  that  cattle  from  his  ranch  have  been  condemned  as 
unfit  for  food  on  account  of  tuberculosis. 

Reports  of  meat  inspectors  in  San  Francisco  show  that  the  number 
of  tuberculous  cattle  coming  from  certain  sections  increased  from 
nine-tenths  of  one  per  cent  to  nine  per  cent  in  five  years.  Recently 
the  proportion  of  hogs  condemned  by  meat  inspectors  on  account  of 
tuberculosis  has  increased  markedly.  This  is  an  added  indication  of 
the  spread  of  infection  in  cattle  since  the  cow  is  the  chief  source  of 
tuberculous  infection  in  swine,  the  disease  being  transmitted  to  swine 
through  milk  or  buttermilk  from  tuberculous  cows,  through  infected 
cattle  corrals  or  by  feeding  uncooked  carcasses  to  the  hogs.  The 
enormous  losses  due  to  this  disease  are  a  tax  upon  every  pint  of  milk 
and  every  pound  of  beef  sold.  That  the  aggregate  loss  to  the  state 
is  enormous  cannot  be  doubted,  but,  on  the  other  hand,  the  loss  to 
the  individual  owner  is  seldom  so  great  as  to  make  him  ready  to 
adopt  measures  involving  a  great  deal  of  immediate  trouble  and 
expense,  in  order  to  secure  eventual  complete  freedom  from  the  disease. 

WHAT  ARE  THE  SYMPTOMS  OF  TUBERCULOSIS  IN  CATTLE? 

There  is  no  symptom  that  can  be  relied  upon  with  certainty.  A 
herd  may  be  badly  infected  and  yet  none  of  the  cattle  show  symptoms 
of  ill  health.  Tuberculosis  may  attack  almost  any  organ  of  the  body, 
but  until  it  has  progressed  to  an  advanced  stage  there  may  be  no 
visible  signs.  Following  are  some  of  the  more  important  symptoms 
suggestive  of  the  disease,  but  it  should  be  understood  that  these  may 
also  be  caused  by  other  diseases: 

Unthriftiness. — In  advanced  stages  of  the  disease  the  coat  may 
become  rough,  the  hair  failing  to  shed  readily  with  the  change  of 

The  new  law  gives  this  alternative:  either  to  pasteurize  the  milk  and  cream 
sold  at  retail  or  to  submit  the  cattle  to  an  official  tuberculin  test.  Dairymen 
who  sell  in  bulk  to  the  wholesale  trade  need  not  have  their  cows  tested  or  install 
a  pasteurizer.  The  responsibility  of  pasteurization  rests  on  the  creamery.  In 
cities  or  counties  having  a  dairy  inspection  service  all  milk  retailed  must  be 
graded  and  properly  labeled. 

Every  cow  owner  who  intends  to  retail  any  unpasteurized  milk  or  other 
dairy  product,  except  cheese,  should  write  to  The  State  Veterinarian,  Sacramento, 
California,  requesting  that  his  cows  be  tuberculin  tested.  Those  intending  to 
retail  in  any  city  or  county  having  a  dairy  inspection  service  should  file  a 
duplicate  request  with  the  local  health  officer.  After  filing  these  requests  the  dairy- 
man is  not  liable  under  the  provisions  of  the  law  until  the  State  Veterinarian 
or  his  representative  shall  be  able  to  make  the  required  tests. 

Pasteurization  on  the  dairy  ranch  will  in  most  cases  be  impracticable.  Any 
dairyman  who  is  contemplating  the  installation  of  pasteurization  equipment  is 
advised  to  confer  with  the  officials  of  the  State  Dairy  Bureau  or  with  the 
chief  dairy  inspector  of  the  city  in  which  his  products  are  used,  for  many  cities 
refuse  to  allow  milk  to  be  sold  unless  it  has  been  pasteurized  within  the  cites. 
It  is,  moreover,  illegal  to  repasteurize  milk  to  be  sold  for  human  consumption. 


seasons.  The  skin  loses  its  suppleness  and  feels  harsh  and  thick 
and  is  difficult  to  fold  when  grasped  by  the  hands.  This  is  especially 
noticeable  in  the  neck  or  flanks.  This  condition  is  known  as  "hide- 
bound." The  debilitated  expression  of  the  eyes  and  face,  the  bristling 
hair,  arched  back  and  tucked-up  abdomen  are  symptoms  which  may 
or  may  not  be  present  in  advanced  tuberculosis. 

Loss  of  Flesh. — A  gradual  falling  away  should  always  be  a  cause 
for  suspicion,  but  leanness  is  a  common  characteristic  of  good  dairy 
cows ;  therefore  a  knowledge  of  the  normal  for  each  individual  animal 
is  necessary  before  judgment  may  be  passed  on  this  symptom.  The 
owner  or  milker  is  often  better  qualified  to  decide  these  cases  than  a 
veterinarian  who  has  never  seen  the  animal  before. 

Cough. — This  symptom  is  only  present  when  the  disease  is  attack- 
ing the  lungs  or  some  part  of  the  breathing  organs.  It  is  usually  rather 
subdued  and  infrequent  and  may  occur  only  when  the  animal  is  driven 
or  when  she  gets  up  after  having  lain  down  for  some  time.  Tubercu- 
lous cows  do  not  appear  to  cough  up  anything.  This  may  be  because 
they  cannot  spit.  Most  of  the  material  coughed  up  from  the  lungs 
is  swallowed,  but  many  tuberculosis  germs  escape  from  the  mouth  in 
the  spray. 

Nasal  Discharge. — A  slight  discharge  of  pus  from  the  nostrils  may 
occur  in  cattle  with  advanced  tuberculosis  of  the  lungs.  This  discharge 
is  often  concealed  by  the  frequent  licking  of  the  nostrils  and  would 
be  overlooked  by  any  but  a  close  observer. 

Enlarged  Glands. — Hard,  painless  swellings  in  cattle  are  apt  to 
be  due  to  tuberculosis.  These  are  especially  liable  to  occur  in  front 
of  the  shoulder,  in  the  flank  or  groin,  or  in  the  region  of  the  throat. 
Swellings  under  the  jaw  proper  are  more  often  due  to  actinomycosis 
or  to  the  penetration  of  the  tissues  by  foxtail  beards.  Tuberculous 
growths  often  develop  in  the  throat  or  back  of  the  jaws  so  as  to 
produce  a  roughened  sound  in  breathing. 

Hard  Lumps  in  the  Udder. — When  tuberculosis  attacks  the  udder 
no  change  can  be  detected  at  first,  but  after  a  time  hard  lumps  can 
be  felt  in  some  parts  of  the  organ  after  it  is  milked  out.  Milk  from 
such  an  udder  must  not  be  used. 

Chronic  Bloating. — Sometimes  the  diseased  glands  in  the  chest 
prevent  the  usual  passage  of  gas  from  the  paunch  to  the  mouth  by 
pressing  on  the  gullet.  The  resulting  bloat  is  recurrent  or  chronic 
and  easily  distinguishable  from  the  acute  bloating  caused  by  green 
alfalfa. 


Diarrhoa. — Looseness  of  the  bowels  or  "scouring"  is  seen  in  ad- 
vanced stages,  particularly  when  the  disease  is  generalized.  This  kind 
of  scouring  does  not  yield  to  treatment. 

WHAT  TUBERCULOSIS  IN  CATTLE  LOOKS  LIKE 

When  the  carcass  of  the  cow  affected  with  tuberculosis  is  opened, 
the  disease  may  be  found  in  any  part  of  the  body,  but  it  is  usually 
located  in  the  lymph  glands  of  the  chest,  throat,  or  abdomen.  The 
exteriors  of  the  tubercles  often  look  like  masses  of  pearls  and  on  this 
account  years  ago  the  disease  was  called  pearl  disease  of  cattle. 
Tissues  showing  lesions  of  tuberculosis  in  cattle  and  hogs  can  be  seen 
in  the  veterinary  exhibits  of  the  College  of  Agriculture  at  Berkeley 

THE  CAUSE  OF  TUBERCULOSIS  IN  CATTLE 

Although  there  is  much  that  is  yet  to  be  satisfactorily  explained 
concerning  the  way  in  which  cattle  contract  tuberculosis,  it  is  definitely 
known  that  the  disease  results  from  the  invasion  of  the  tissues  of  the 
body  by  bacteria.2  The  bacilli  of  bovine  tuberculosis  are  believed  to 
exist  only  in  the  tissues  of  diseased  animals  and  in  their  excretions, 
or  on  substances  contaminated  by  these  excretions.  Except  under 
the  most  favorable  conditions  they  do  not  multiply  outside  the  body, 
although  if  not  killed  by  sunlight  or  disinfectants  they  may  survive 
in  dirt  for  several  months. 


2  The  Bacillus  tuberculosis  (Koch)  belongs  to  that  genus  of  microscopic- 
plants  known  as  discomyces  or  mycobacteria.  When  the  infected  tissue  is 
smeared  on  a  glass  slide  and  properly  stained  the  bacteria  may  be  seen  by 
means  of  a  high-power  microscope  as  slender,  slightly  bent  rods,  .00006  to  .00015 
inch  in  length  by  .00001  to  .00002  inch  in  diameter.  These  organisms  do  not 
stain  readily  with  ordinary  aniline  dyes.  Once  stained  with  carbol-fuchsin, 
however,  the  dye  is  retained  even  after  the  application  of  alcohol  or  30  per  cent 
sulphuric  or  hydrochloric  acid.  For  this  reason  tubercle  bacilli  and  a  few  other 
species  of  bacteria  are  classed  as  ' '  acid  and  alcohol  fast, ' '  as  distinguished 
from  those  which  lose  the  color  of  their  stain  when  treated  with  alcohol  and 
acid.  Tubercle  bacilli  are  not  readily  obtained  in  pure  culture  from  tuberculous 
tissues.  The  usual  method  is  to  inoculate  guineapigs  and  from  their  diseased 
tissues  inoculate  a  large  number  of  tubes  containing  egg  media.  When  once 
started  to  grow  on  egg  media  the  germs  can  be  transferred  and  more  readily 
cultivated  on  glycerine  bouillon. 

Tubercle  bacilli  of  cattle,  man  and  birds  may  be  distinguished  from  one 
another  by  appropriate  laboratory  methods.  A  culture  of  bovine  tubercle 
bacilli  may  be  distinguished  from  the  human  type  by  the  fact  that  it  grows 
feebly  and  the  acidity  of  the  bouillon  decreases,  while  the  growth  of  the  human 
type  is  luxurious  and  the  media,  although  first  reduced  in  acidity,  become  more 
and  more  acid  with  the  age  of  the  culture.  The  human  and  bovine  types  appear 
to  be  equally  virulent  for  guineapigs.  The  human  variety  is  not  often  fatal  to 
rabbits  or  cattle  and  the  tissue  changes  which  it  produces  in  these  are  very 
slight  and  restricted  to  the  point  of  inoculation.  The  bovine  variety  when 
inoculated  into  cattle  or  rabbits  is  usually  fatal. 


HOW  THE  DISEASE   SPREADS 

When  an  animal  first  becomes  infected  there  is  usually  no  danger 
to  other  cattle,  but  sooner  or  later  tuberculous  cattle  begin  to  give  off 
the  germs  of  the  disease.  The  germs  escape  through  the  mouth  and 
nose,  the  bowels,  the  milk  and  with  discharges  from  the  genital  organs. 
When  the  disease  is  located  in  the  lungs  and  discharges  into  the  air 
tubes,  pieces  of  diseased  tissue  and  millions  of  germs  are  liberated 
and  coughed  up.  Most  of  these  are  swallowed  and  passed  out  in 
the  manure.  This  is  the  chief  way  in  which  the  germs  are  discharged 
from  diseased  cattle.  When  the  germs  are  being  given  off  in  any  of 
these  ways,  the  disease  is  known  as  open  tuberculosis.  Cattle  in 
advanced  stages  of  the  disease  usually  have  open  tuberculosis.  The 
high  percentage  of  tuberculous  cattle  and  hogs  on  certain  ranches 
has  been  found  to  be  due  to  the  failure  of  the  owners  to  remove 
promptly  animals  that  develop  visible  indications  of  the  disease. 

Germs  discharged  from  the  mouth  and  nose  are  coughed  up  from 
the  lungs  and  are  sprayed  over  the  food  in  front  of  the  cow  or  are 
carried  in  the  air  for  a  time  until  they  fall  to  the  ground.  Cows  in 
adjoining  stalls  may  take  in  these  germs  in  the  air  they  breathe  or 
in  the  food  they  eat,  and  so  contract  the  disease. 

Germs  discharged  from  the  bowels  are  mixed  with  the  manure 
and  may  infect  cattle  and  hogs  that  are  allowed  to  pick  over  the  dung 
heap.  The  practice  of  having  hogs  and  cattle  together  in  the  same 
yard  often  results  in  the  infection  of  the  hogs,  if  any  of  the  cattle 
are  affected.  Manure  containing  tuberculosis  germs  may  easily  infect 
the  milk.  Particles  of  dried  manure  may  fall  into  the  milk  pail  from 
the  skin  of  a  dirty  cow  or  be  accidentally  flicked  off  from  the  tail  and 
fall  into  the  milk.  Straining  the  milk  afterwards  only  removes  the 
larger  particles.  The  smaller  ones,  including  the  germs,  remain  in 
the  milk.  When  the  udder  is  tuberculous,  the  milk  contains  the  germs 
in  vast  numbers.  Although  such  milk  may  look  and  taste  perfectly 
good,  it  may  transmit  the  disease  to  young  animals.  Hogs  and  calves 
are  readily  infected  by  it.     It  is  also  dangerous  to  children. 

When  all  the  tuberculous  areas  in  the  body  are  so  situated  that 
no  germs  are  being  given  off  or  discharged  in  the  secretions,  as  above 
described,  the  condition  is  known  as  closed  tuberculosis.  Such  animals 
do  not  transmit  the  infection  until  they  become  so  diseased  that  the 
tuberculous  areas  open  into  a  passage  leading  to  the  exterior  of  the 
body.  Many  infected  cattle  never  develop  open  tuberculosis,  but  there 
is  no  way  of  determining  accurately  in  living  cattle  which  are  the 
open  cases  and  which  are  closed.     In  badly  infected  herds  a  careful 


physical  examination  by  a  veterinarian  will  eliminate  a  certain  pro- 
portion and  a  much  larger  proportion  may  be  detected  by  the  inocula- 
tion of  guinea  pigs.  This  latter  procedure,  however,  is  impracticable 
under  average  dairy  conditions  and  it  will  fail  to  detect  those  cases 
which  do  not  happen  to  discharge  germs  at  the  exact  time  the  sample 
is  taken. 

Rate  of  Development. — Individual  animals  exhibit  the  widest  vari- 
ation in  the  duration  of  the  disease.  In  the  majority  the  disease 
pursues  a  leisurely  course,  consuming  years  before  causing  death. 
Most  infected  cattle  are  fattened  and  sold  for  beef,  but  some  develop 
a  rapidly  fatal  type.  Its  onset  is  always  unobtrusive  and  its  progress 
is  so  gradual  that  its  presence  does  not  cause  apprehension.  Losses 
are  so  evenly  distributed  in  point  of  time  that  they  do  not  excite 
serious  alarm,  as  do  other  less  destructive  diseases  of  the  pestilential 
type  which  kill  many  suddenly.  The  rate  of  spread  in  a  herd  is  vari- 
able. In  some  herds  which  are  known  to  have  a  few  reacting  animals 
the  disease  does  not  seem  to  spread.  Perhaps  this  is  due  to  the  fact 
that  few,  if  any,  of  these  happen  to  be  open  cases.  On  the  other  hand, 
in  certain  instances  under  observation  the  disease  has  been  introduced 
into  clean  herds  and  in  a  few  months,  through  the  development  of 
open  cases,  a  large  proportion  of  the  cattle  have  become  reactors.  The 
feeding  of  infected  milk  to  calves,  particularly  unheated  mixed  skim- 
milk  returned  from  the  creamery,  usually  results  in  speedy  infection. 

HOW  A  HEED  IS  INFECTED 

Tuberculosis  may  be  introduced  into  a  healthy  herd  in  a  number 
of  ways: 

1.  By  the  purchase  of  a  bull  or  other  animal  that  is  infected  with 
the  disease.  This  animal  may  be  apparently  healthy  at  the  time  of 
purchase,  but  if  previously  exposed  the  disease  may  develop  and 
spread  to  other  cattle.  Where  a  healthy  herd  is  being  maintained, 
animals  should  only  be  bought  subject  to  the  tuberculin  test  and  even 
this  precaution  may  fail  if  the  herd  from  which  they  come  is  badly 
infected. 

2.  By  feeding  calves  with  milk,  buttermilk,  or  whey  that  has  come 
from  tuberculous  cows.  A  farmer  may  have  a  healthy  herd,  but,  if 
he  brings  home  skim-milk  from  a  creamery  and  feeds  it  to  his  calves, 
the  disease,  if  present  in  the  milk,  may  be  transmitted  to  them.  Such 
milk  should  be  rendered  safe  by  boiling  or  pasteurizing. 

3.  By  showing  cattle  at  fairs  and  exhibitions  where  proper  care 
is  not  taken  to  keep  out  diseased  stock,  or  to  disinfect  the  stables. 


4.  By  shipping  animals  in  cars  that  have  not  been  disinfected,  as 
these  may  have  recently  carried  diseased  cattle. 

5.  By  allowing  the  cattle  to  graze  with  diseased  ones,  or  to  come 
into  contact  with  them  over  fences. 

6.  When  the  cattle  are  permitted  access  to  small  ponds,  water  holes, 
or  troughs,  these  may  become  badly  contaminated  with  infected  manure 
from  "open  cases/'  The  rapid  spread  of  the  disease  on  certain  ranges 
is  believed  to  be  due  in  part  to  infected  water. 

HOW   THE   PRESENCE    OF   TUBERCULOSIS   INFECTION   MAY 
BE   DEMONSTRATED 

The  tuberculin  reaction  is  the  best  method  at  present  available 
for  the  recognition  of  tuberculous  infection  in  cattle.  There  are 
several  reasons  why  this  special  test  is  necessary.  Unless  cattle  are 
very  badly  diseased  they  seldom  show  symptoms  of  ill  health.  Almost 
any  organ  of  the  body  may  be  attacked,  but  until  the  abnormal  pro- 
cess has  progressed  far  enough  to  interfere  seriously  with  some  func- 
tion no  symptoms  can  be  detected.  The  thickness  of  the  skin  and 
chest  wall  makes  it  difficult  to  detect  a  diseased  condition  in  a  cow's 
lung  by  listening  to  the  sounds  made  in  breathing,  whereas  this  is 
comparatively  easy  in  human  beings.  Next  to  the  tuberculin  test, 
a  careful  physical  examination  by  a  trained  veterinarian  is  the  most 
practicable  method  of  diagnosis;  in  fact,  the  tuberculin  test  should 
always  be  supplemented  by  such  an  examination,  since  badly  diseased 
cattle  often  do  not  react  to  the  test. 

Other  methods  which  occasionally  may  be  useful  in  detecting  the 
disease  are  microscopic  examination  of  diseased  tissue,  exudates  from 
the  pulmonary,  intestinal  or  urinary  tracts  and  pus  from  abscesses, 
or  animal  inoculation  with  such  material.  The  latter  is  a  much  more 
certain  test  than  a  direct  miscroscopic  examination.  Guineapigs  are 
usually  employed  for  this  purpose. 

What  is  Tuberculin  and  its  Reaction?  Tuberculin  is  the  filtered, 
sterilized  and  preserved  glycerine  bouillon  upon  which  tubercle  bacilli 
have  grown.  It  contains  no  germs  and  is  harmless  to  cattle  even  in 
increased  dosage.  In  tuberculous  cattle  it  produces  a  temporary  effect 
or  reaction.  The  living  tissues  of  tuberculous  persons  and  animals  are 
sensitive  to  tuberculin.  This  sensitiveness  is  most  marked  in  the  tis- 
sues that  are  actually  invaded  by  the  germs,  but  it  also  exists  to  some 
extent  in  the  other  tissues  of  the  body  which  contain  bloodvessels. 
The  living  tissues  of  individuals  not  infected  with  tuberculosis  show 
no  sensitiveness  to  tuberculin. 


8 

When  tuberculin  is  injected  into  the  vascular  layers  of  the  skin  of 
a  tuberculous  cow  a  swelling  will  usually  follow.  When  dropped  on 
the  eyeball  an  exudate  of  pus  may  result.  When  injected  into  the 
skin  or  tissues  in  sufficient  amount  a  feverish  attack  comes  on  about 
eight  to  twenty  hours  after  the  tuberculin  is  administered,  lasts  a  few 
hours  and  then  subsides.  These  symptoms  are  called  reactions  and 
animals  which  show  them  are  called  reactors.  The  value  of  the  test 
lies  in  the  fact  that  diseased  animals  react,  while  healthy  ones  do  not. 

There  are  several  ways  of  testing  with  tuberculin.  The  methods 
which  are  most  practicable  are  the  intradermal,  the  subcutaneous  and 
the  ophthalmic.  Each  of  these  methods  has  certain  advantages.  The 
conditions  under  which  the  testing  is  to  be  performed  should  be  the 
guide  in  choosing  the  method.  The  successive  or  combined  use  of  all 
three  tests  on  the  same  animals  gives  the  highest  accuracy  in  diagnosis. 


THE  INTRADERMAL  METHOD 

The  tuberculin  is  injected  into  the  deeper  layers  of  the  skin,  or  into  the  sub- 
dermal  tissue  immediately  adjacent,  in  %0  to  %  c.c.  amounts,  depending  on  the 
concentration  of  the  tuberculin  used.  A  hypodermic  syringe  with  a  short  needle- 
point should  be  used.  Such  a  syringe  should  have  a  25  or  26  gauge  needle  with 
a  point  three-sixteenths  to  one-quarter  of  an  inch  in  length,  similar  to  those 
used  by  dentists  for  injecting  local  anesthetics.  The  most  suitable  place  to 
make  this  injection  is  one  of  the  folds  of  the  skin  on  the  under  side  of  the  base 
of  the  tail. 

Standing  against  the  right  flank  of  the  cow,  the  left  subcaudal  fold  is 
grasped  between  the  thumb  and  the  first  two  fingers  of  the  left  hand  and  the 
needle  inserted  into  that  portion  of  the  skin  held  between  the  thumb  and  finger. 
The  dose,  if  properly  placed,  can  be  felt  as  it  is  expelled  from  the  syringe  in 
the  layers  of  the  skin,  where  it  remains  as  a  small  lump  in  the  skin  after  the 
needle  has  been  removed.  The  mistake  of  trying  to  inject  as  near  the  surface 
of  the  skin  as  possible  should  be  avoided.  It  is  difficult  to  inject  into  the  layers 
of  the  epidermis  and  an  injection  into  this  part  of  the  skin  is  of  little  diagnostic 
value.  In  case  the  needle  is  of  the  proper  length,  namely,  one-quarter  of  an 
inch,  there  is  little  danger  of  going  completely  through  the  skin.  When  the 
proper  point  in  the  subcaudal  fold  is  selected,  it  makes  little  difference  whether 
the  point  of  the  needle  is  in  the  dermal  or  in  the  subdermal  connective  tissue. 
It  is  well  to  inject  at  a  point  on  the  fold  about  two  and  one-half  or  three  inches 
down  the  tail  from  the  anus,  since  elsewhere  reactions  are  not  so  easily  per- 
ceived, and  at  this  point  the  bone  and  solid  tissue  of  the  tail  form  a  background 
which  renders  the  local  reactions  prominent. 

The  skin  of  the  lower  eyelid  has  been  used  in  some  of  the  tests  at  this 
station,  but  the  subcaudal  fold  has  been  found  to  be  more  satisfactory.  This 
method  of  injecting  the  tuberculin  intradermally  into  the  lower  eyelid  is 
called  the  intrapalpebral  test  and  has  been  advocated  by  certain  veterinarians 
as  a  cleaner  and  more  convenient  way  to  administer  the  test.  It  is,  however, 
loss  practicable  on  account  of  the  additional  help  needed.     The  reactions  are  at 


9 

times  difficult  to  distinguish  from  the  normal  fullness  of  the  lower  eyelid,  and 
on  this  account  it  is  necessary  to  examine  and  compare  the  tissues  beneath  both 
eyes  in  deciding  a  reaction.    It  is  a  difficult  method  to  use  on  range  cattle. 

The  Beaction  to  the  Intradermal  Injection  in  Cattle.  A  positive  intradermal 
reaction  is  indicated  by  a  thickening  of  the  subcaudal  fold  or  by  the  appearance 
at  the  point  of  injection  of  a  characteristic  sensitive  swelling  varying  in  size 
from  that  of  a  pea  to  that  of  an  orange.  The  swelling  may  be  either  soft  and 
oedematous  or  hard  and  inflamed.  The  majority  of  reactions  are  seldom  clear 
before  the  twelfth  hour  and  when  testing  in  infected  herds  new  reactors  continue 
to  appear  until  the  seventieth  hour.  In  some  instances  we  have  observed  that 
the  early  local  reactions  disappear  before  the  forty-eighth  hour,  while  in  several 
cases  we  noted  reactions  which  did  not  appear  until  the  ninetieth  hour.  In 
order  to  be  certain  of  every  case,  observations  must  be  taken  at  least  twice, 
preferably  about  the  thirty-sixth  and  seventy-second  hours.  If  only  one  obser- 
vation can  be  made,  it  should  be  on  the  seventy-second  hour.  Small  indurations 
at  the  point  of  inoculation  about  the  size  of  the  head  of  a  parlor  match  frequently 
occur  in  normal  non-reacting  cattle,  but  any  larger  than  this  which  persist  to  the 
seventy-second  hour  should  be  considered  a  positive  reaction. 

In  judging  a  local  swelling,  the  observer  should  depend  more  upon  the  shape, 
appearance,  tenseness,  sensitiveness  and  location  with  respect  to  the  exact  point 
of  injection  than  upon  actual  measurements.  Only  experience  can  teach  an 
operator  how  to  be  certain  of  a  positive  reaction  when  the  local  swelling  is 
small.  This  is  especially  true  when  tuberculin  containing  glycerine  has  been 
used.  Usually  tuberculous  cattle  also  show  a  temperature  reaction  to  the  intra- 
dermal injection. 

THE  OPHTHALMIC  METHOD 

An  assistant  should  grasp  the  animal  by  the  nose  and  turn  the  head  at  an 
angle  so  that  the  operator  may  drop  one  or  two  drops  of  the  tuberculin  directly 
upon  the  eyeball.  A  small  hypodermic  syringe  with  the  needleshank  broken  or 
filed  off  is  more  suitable  for  this  purpose  than  a  medicine  dropper.  The  eye  is 
then  closed  for  a  few  seconds  by  pressure  from  the  palm  of  the  hand.  A  pre- 
liminary instillation  to  render  the  eye  sensitive  should  first  be  given  as  just 
described,  but  it  is  not  necessary  to  take  observations  concerning  the  results  of 
this.  The  second  or  test  instillation  is  made  in  the  same  eye  in  from  three  to 
fourteen  days.  The  reaction  in  tuberculous  cattle  usually  sets  in  by  the  eighth 
hour.  In  cattle  whose  eyes  have  been  sensitized  by  a  previous  instillation  it 
may  set  in  by  the  third  hour.  It  manifests  itself  by  a  purulent  exudate  which 
accumulates  at  the  inner  corner  of  the  eye  and  usually  runs  down  the  face. 
This  sometimes  dries  up  and  drops  off  in  a  few  minutes,  so  that  the  evidence  of 
the  reaction  may  quickly  and  entirely  disappear,  although  occasionally  pus 
discharge  can  be  seen  for  several  days.  Although  the  results  of  the  test  are 
usually  apparent  by  the  twelfth  hour,  they  may  occur  as  early  as  the  third 
hour,  and  observations  should  be  made  as  frequently  as  practicable  from  the 
third  to  the  twenty-fourth  hour.  The  test  is  only  satisfactory  when  cattle  can 
be  kept  tied  or  confined  in  stanchions  under  shelter  for  a  period  of  at  least 
16  hours,  except  in  the  case  of  cattle  which  show  a  reaction  before  that  time. 
It  is  advisable  not  to  feed  unchopped  hay  on  account  of  the  possibility  of 
wiping  off  the  exudate. 


10 


THE  SUBCUTANEOUS  METHOD 

This  method  consists  in  injecting  one  to  four  cubic  centimeters  of  tuberculin 
beneath  the  skin  of  the  neck  or  shoulders.  The  reactions  consist  of  a  feverish 
attack,  characterized  by  a  rise  in  temperature  and  occasionally  by  symptoms 
of  depression,  shivering,  bristling  hair,  ceased  rumination  and  looseness  of  the 
bowels.  In  some  cases  these  symptoms  are  noticeable,  while  in  others  they  do 
not  appear  at  all.  The  temperature  rise  after  the  injection  of  tuberculin  in  a 
tuberculous  animal,  however,  is  seldom  absent  and  usually  occurs  between  the 
eighth  and  the  twentieth  hours.  The  normal  temperature  of  a  cow  varies 
between  100°  F.  and'  103°  F.  Calves  and  fat  stock  may  range  to  103.5°  F. 
During  the  tuberculin  reaction  the  temperature  rises  to  a  height  varying  be- 
tween 103°  F.  and  108°  F.  The  positive  tuberculin  reaction  generally  shows 
a  regular  rise,  the  temperature  remaining  at  the  highest  point  for  a  short  time, 
then  falling  gradually  to  normal.  The  highest  point  is  usually  between  104°  F. 
and  107°  F.,  but  in  some  reactors  may  be  as  low  as  103.2°  F.  and  in  others 
reach  108°  F.  It  is  not  always  an  easy  matter  to  distinguish  between  some 
reactions  and  the  variations  in  temperature  in  the  normal  healthy  animals. 
The  temperature  of  cattle  is  quite  erratic,  being  influenced  by  the  weather  or 
any  change  in  the  usual  routine  of  handling.  During  the  severe  north  winds 
which  sometimes  occur  in  central  California  the  temperature  of  herds  of  normal 
cattle  may  average  over  103.5°  F. 

Directions  for  Talcing  Temperatures.  Continue  the  normal  temperatures  until 
they  drop  below  103°  F.  Take  subsequent  temperatures  every  two  hours  be- 
tween the  eighth  and  twentieth  hour.  If  any  subsequent  temperature  reaches 
103°  F.,  take  another  temperature  in  one  hour.  If  at  the  twentieth  hour  after 
injection  any  animal  shows  a  rise  in  temperature  above  previous  temperatures 
for  the  day  continue  taking  the  temperature  as  long  as  the  rise  is  continued. 


WHEN  THE  VAEIOUS  METHODS  SHOULD  BE  USED 

The  intradermal  method  is  the  form  of  the  test  which  will  be  used 
in  most  cases  by  the  State  Veterinarian  in  enforcing  the  new  dairy 
law.  Since  the  reaction  to  tuberculin  when  injected  intradermally 
depends  upon  a  swelling  at  the  point  of  injection  and  not  on  a  rise  of 
temperature,  it  is  to  be  preferred  to  the  subcutaneous  method  under 
all  conditions  which  are  liable  to  modify  the  tuberculin  temperature 
curve.  It  can  be  satisfactorily  applied  to  calves  and  wild  range  cattle 
and  is  especially  useful  in  testing  cattle  during  the  hot  season  in  the 
interior  valleys  of  this  state  under  conditions  rendering  both  the  sub- 
cutaneous and  ophthalmic  methods  of  testing  unsatisfactory.  It  excels 
these  methods  in  economy  of  time,  labor  and  materials. 

The  ophthalmic  method  is  desirable  where  favorable  arrangements 
can  be  made  for  housing  the  cattle  during  the  test  and  when  there  is 
time  to  repeat  the  test.  The  chief  advantages  are:  (1)  It  does  not 
render  the  cattle  insensitive  to  subsequent  tests  by  other  methods.     (2) 


11 

It  will  cause  reactions  in  tuberculous  cattle  that  have  been  "plugged," 
i.e.,  treated  with  tuberculin  to  render  them  insensitive  to  a  test.  (3) 
The  technique  of  the  test  is  simple  and  the  interpretation  of  the  re- 
actions requires  less  skill  and  experience  than  the  intradermal  reac- 
tions. (4)  In  case  of  doubtful  reactions,  the  test  may  be  repeatedly 
administered  to  the  same  animal. 

The  subcutaneous  method  is  the  original  way  of  testing  and  is  the 
only  method  officially  accepted  in  all  states  and  by  the  United  States 
Department  of  Agriculture.  On  account  of  its  extensive  use  for  many 
years  its  possibilities  and  limitations  are  understood  by  nearly  all 
veterinarians  and  by  many  stock  owners.  Its  proper  application  re- 
quires less  practice  and  the  results  can  be  more  readily  interpreted 
by  the  inexperienced.  The  record  of  the  reactions  can  be  graphically 
expressed  in  the  form  of  a  temperature  curve.  The  use  of  this  method 
is  especially  to  be  commended  in  infected  herds  as  an  additional  pre- 
caution to  be  applied  following  the  use  of  the  other  two  tests. 

LIMITATIONS  OF  THE  VARIOUS  METHODS  OF  TESTING 

No  form  of  the  tuberculin  test  distinguishes  between  severe  and 
slight  cases,  nor  between  those  that  are  spreading  infection  and  those 
that  are  not  inconvenienced  by  the  disease  and  are  not  infecting  others. 
The  test  is  so  searching  that  extremely  slight  infection  will  cause  the 
animal  to  react.  In  cattle  reacting  to  the  test  the  infection  may  occa- 
sionally be  so  recent  and  the  changes  so  slight  that  the  ordinary  methods 
of  post-mortem  examination  fail  to  demonstrate  the  presence  of  tuber- 
culosis, since  the  lesions  may  be  microscopic  in  size.  If  a  reaction 
does  occur,  tuberculosis  is  certainly  present,  although  it  may  be  very 
slight ;  but  if  no  reaction  occurs  care  must  be  taken,  for  there  is  still 
a  possibility  that  the  disease  is  present.  Following  are  some  of  the 
factors  to  be  considered : 

(1)  The  animal  may  not  react  if  very  extensively  tuberculous, 
but  in  such  cases  physical  symptoms  will  usually  indicate  ill  health. 

(2)  The  reaction  does  not  occur  during  the  period  of  incubation 
of  the  disease;  in  infected  herds  a  second  test  should,  therefore,  be 
made  within  six  months. 

(3)  Cows  that  have  once  reacted  may  fail  to  do  so  upon  subsequent 
tests,  the  lesions  being  encapsulated  or  arrested,  but  frequently  in 
such  cases  the  disease  is  known  to  have  become  active  again  after  a 
time. 

(4)  The  possibility  of  the  cattle  having  been  "plugged"  by  the 
previous  injection  of  tuberculin  must  sometimes  be  taken  into  account. 


12 

The  discovery  that  the  ophthalmic  test  will  usually  cause  reactions  in 
' '  plugged ' '  tuberculous  cattle  has  somewhat  decreased  the  importance 
of  the  chance  of  error.  Dr.  James  Law  in  his  treatise  on  veterinary 
medicine  gives  seventeen  conditions  under  which  he  believes  the  sub- 
cutaneous method  to  be  unreliable.  In  most  instances  these  do  not 
apply  to  the  intradermal  or  ophthalmic  methods.  Only  those  who 
have  been  especially  trained  and,  in  addition,  have  had  considerable 
field  experience  can  secure  accurate  results  in  testing  badly  infected 
herds.  Each  form  of  the  test  has  its  special  value  and  limitations. 
Nevertheless,  the  tuberculin  test  must  be  looked  upon  as  the  most 
accurate  and  valuable  means  at  hand  to  assist  in  the  diagnosis  of 
tuberculosis. 

(5)  Frequently  tuberculous  animals  have  been  observed  to  react 
to  one  form  of  test  and  fail  to  respond  to  the  others.  This  peculiarity 
in  some  infected  animals  has  not  been  satisfactorily  explained,  al- 
though the  proportion  of  such  animals  is  sufficient  to  be  of  consider- 
able practical  importance.  A  large  proportion  of  such  cases  may  be 
due  to  lack  of  sufficient  care  to  observe  the  effects  of  the  tuberculin 
upon  the  individual,  i.e.,  failure  in  the  subcutaneous  test  to  take  suffi- 
cient temperatures ;  failure  in  the  intradermal  test  to  inspect  the  point 
of  injection  at  proper  intervals ;  failure  in  the  ophthalmic  test  to  keep 
the  animals  under  proper  environment  and  constant  observation. 

THE  COMBINED  OE  FOLLOW-UP  SYSTEM  OF  TUBERCULIN  TESTING 

In  badly  infected  herds  the  maximum  efficiency  by  the  ordinary 
technique  used  by  veterinarians  in  routine  work  probably  averages 
less  than  90  per  cent  for  any  one  method  of  tuberculin  testing,  the 
errors  being  due  chiefly  to  failures  to  secure  or  detect  reactions  in  the 
tuberculous  cattle.  Before  accrediting  a  previously  infected  herd  as 
free  from  tuberculosis,  the  veterinarian  should  use  the  combined 
methods.  The  following  procedure,  which  we  have  called  the  follow- 
up  system,  is  advised : 

(1)  Apply  the  ophthalmic  test  two  times  at  intervals  of  about  one 
week,  the  results  of  the  second  test  being  watched  with  great  care. 

(2)  Follow  this  by  the  intradermal  test,  using  y5  c.c.  of  a  strong 
tuberculin  solution,  such  as  10  per  cent  precipitated  tuberculin,  and 
take  temperatures  as  in  the  subcutaneous  test  above  described.  Ex- 
amine the  point  of  injection  for  local  reaction  at  about  the  36th  and 
72nd  hours.  In  case  the  herd  is  to  be  retested  by  the  subcutaneous 
method,  the  taking  of  temperatures  may  be  omitted  and  the  intrader- 
mal dose  reduced  to  Mo  c.c.  of  ordinary  veterinary  or  5  per  cent  pre- 
cipitated tuberculin. 


13 

(3)  After  a  lapse  of  at  least  six  weeks,3  the  subcutaneous  method 
may  be  applied  to  all  animals  that  have  not  been  removed  by  the  pre- 
vious tests.  The  additional  precaution  of  occasional  ophthalmic  tests 
is  sometimes  also  desirable. 

(4)  All  herds  having  reactors  should  be  retested  every  six  months 
and  herds  free  from  reactors  annually. 

This  station  has  found  the  above  system  desirable  in  building  up  a 
clean  herd  where  the  only  supply  of  animals  was  from  very  badly 
infected  herds.  For  a  number  of  years  the  alternate  use  of  the  intra- 
dermal and  subcutaneous  methods  semi-annually  has  been  in  vogue 
in  most  certified  dairies  in  this  state,  and  whenever  an  unusually  large 
percentage  of  reactors  has  been  found  the  follow-up  system  has  been 
used. 

DISPOSING  OF  REACTING  CATTLE 

Slaughter  for  beef  under  inspection  is  the  recommended  method  of 
disposal  of  all  reacting  cattle  which  show  no  visible  signs  of  the  disease, 
except  in  those  cases  where  the  beef  value  would  be  very  much  less 
than  the  dairy  or  breeding  value.  The  method  formerly  and  most 
commonly  employed  of  disposing  of  reacting  animals  was  by  slaughter 
and  burial.  Where  this  wasteful  method  has  been  employed  the  re- 
sults have  been  discouraging;  even  when  the  state  recompensed  the 
owner  in  part  for  the  loss  of  his  stock,  it  has  been  unsatisfactory.  A 
large  number  of  reacting  animals  are  usually  but  slightly  diseased. 
They  readily  take  on  flesh  and  can  be  fattened  and  used  for  beef. 
The  university  practices  what  it  preaches  in  this  regard.  They  must 
be  carefully  examined  by  a  veterinarian  when  killed  and  if  the  disease 
is  found  to  be  extensive  the  carcass  must  be  condemned.  The  federal 
government  meat  inspection  regulations  admit  the  use  of  meat  for 
food  from  animals  that  show  limited  lesions  of  tuberculosis,  for  it  is 
recognized  that  such  meat  does  not  contain  tubercle  bacilli  and,  besides, 
the  common  procedure  of  cooking  meat  is  a  further  safeguard  against 
danger.  The  zeal  of  various  health  officials  in  demanding  the  waste 
of  the  flesh  of  every  reacting  animal  has  been  a  great  drawback  to  the 
control  of  tuberculosis  through  developing  opposition. 

THE  CONTROL  OF  TUBERCULOSIS 
In  the  application  of  any  methods  for  the  eradication  or  prevention 
of  tuberculosis  certain  important  characteristics  of  the  disease  should 
be  borne  in  mind : 


3  The  intradermal  test  appears  to  have  some  modifying  effect  on  a  subse- 
quent test  by  either  the  intradermal  or  subcutaneous  methods,  but  this  is  not  so 
pronounced  as  that  produced  by  the  subcutaneous  injection  and  retests  may 
safely  be  made  in  six  weeks. 


14 

(1)  Its  indigenous  nature.  Bovine  tuberculosis  is  so  firmly  rooted 
and  so  widespread  among  dairy  cattle  that  no  important  dairy  com- 
munity, the  Island  of  Jersey  excepted,  is  free  from  it.  So  far  as  is 
known,  no  dairy  section  when  once  infected  has  been  able  to  eradicate 
the  disease  completely.  The  possibility  of  eradicating  bovine  tuber- 
culosis from  individual  herds  has  been  demonstrated  beyond  all  ques- 
tion, and  the  obstacles  which  have  prevented  the  successful  accom- 
plishment of  this  in  communities,  states,  or  countries  have  been  due 
to  the  unwillingness  of  the  cattle  owners  to  make  the  necessary  finan- 
cial sacrifices. 

(2)  Its  specific  nature.  Tuberculosis  does  not  develop  sponta- 
neously. The  cause  of  the  disease  is  the  bacillus  of  tuberculosis,  which 
exists  only  in  the  bodies  of  tuberculous  animals  and  in  their  secretions, 
or  in  substances  contaminated  by  them.  In-and-in  breeding  cannot 
produce  it.  Dark,  filthy,  badly  ventilated  stables,  poor  food  and 
crowded  conditions  may  contribute  to  its  rapid  spread  among  cattle, 
but  the  disease  does  not  originate  in  an  animal,  no  matter  how  bad  its 
environment.  It  must  be  exposed  to  the  disease  germs  to  contract  the 
disease. 

(3)  Its  infectious  nature.  Tuberculosis  is  most  readily  communi- 
cable. This  point,  in  connection  with  its  specific  nature,  cannot  be  too 
strongly  emphasized.  The  disease  results  from  the  association  of  tuber- 
culous cattle  with  healthy  ones  and  under  such  conditions  will  spread 
in  spite  of  every  sanitary  precaution.  It  is  a  mistake  to  assume  that 
the  disease  cannot  thrive  and  multiply  among  dairy  cattle  kept  under 
ideal  conditions.  The  invigorating  influence  of  fresh  air  and  sunshine, 
wide,  well  watered  pastures,  well  ventilated,  ideally  constructed,  im- 
maculately clean  barns,  and  abundant  and  well  balanced  rations  will 
not  stop,  although  they  are  likely  to  retard  the  spread  of  the  disease. 
It  is  among  some  of  the  best  kept  herds  that  the  disease  has  been  found 
to  be  alarmingly  prevalent.  Contact,  direct  or  indirect,  is  the  chief 
way  in  which  the  disease  is  disseminated.  Calves  most  frequently 
contract  the  disease  from  the  milk.  Calves  and  hogs  fed  on  pasteurized 
milk  from  tuberculous  cows  soon  become  infected. 

STATE  MEASURES  TO  CONTROL  BOVINE  TUBERCULOSIS 

The  responsibility  for  the  spread  of  bovine  tuberculosis  rests  with 
the  owners  of  infected  cattle,  but  it  is  the  duty  of  the  state,  from 
economic  as  well  as  public  health  reasons,  to  aid  them  in  the  difficult 
task  of  controlling  the  increase  of  this  disease  in  live  stock.  In  this 
state,  up  to  the  present  time,  practically  nothing  has  been  done  and 


15 

the  law  soon  to  be  in  force  is  intended  purely  as  a  public  health 
measure. 

Unfortunately,  but  unavoidably,  the  early  efforts  to  eradicate 
bovine  tuberculosis  were  undertaken  without  a  full  appreciation  of 
the  magnitude  of  the  problem.  In  some  states  having  compulsory 
tuberculin  test  laws  the  scheme  of  indemnification  by  the  state  was 
introduced.  With  funds  that  it  has  been  possible  to  get  from  legis- 
latures the  work  has  made  no  progress  and  with  few  exceptions  tuber- 
culosis has  kept  pace  with  the  puny  efforts  directed  against  it.  The 
attempts  by  states  to  eradicate  the  disease  in  cattle  by  tuberculin 
testing  and  the  slaughter  of  all  reacting  animals  have  proved  imprac- 
ticable. 


SUPPRESSION  OF  THE  DISEASE  BY  THE  COW  OWNERS 

The  first  step  in  getting  rid  of  the  disease  is  to  find  out  how  many 
of  the  herd  are  affected.  This  is  done  by  applying  the  combined 
tuberculin  tests  with  careful  physical  examinations.  The  proper 
course  to  pursue  will  depend  largely  upon  the  proportion  of  reactors 
found.  Suppose  a  few  cattle  react,  say  less  than  15  per  cent.  Indi- 
vidual owners  of  such  herds  are  advised  to  start  to  exterminate  the 
disease  immediately.    The  steps  necessary  are : 

1.  Isolate  all  the  reactors,  including  cattle  which  may  have  given 
doubtful  or  questionable  reactions.  Non-reactors  which  on  physical 
examination  show  any  symptoms  attributable  to  tuberculosis  must  be 
included.  It  is  unquestionably  a  good  policy  in  herds  showing  such 
a  low  percentage  of  infection  to  sell  the  reacting  cattle  for  beef,  or 
to  establish  a  separate  infected  herd,  the  milk  of  which  is  pasteurized. 

2.  Thoroughly  clean  and  disinfect  premises.4  Since  chemical  dis- 
infectants in  dilutions  practicable  for  the  liberal  use  required  in  dis- 
infecting stables  and  corrals  act  very  slowly  in  killing  tubercle  bacilli, 
most  dependence  should  be  placed  on  thorough  cleaning,  painting  and 
whitewashing.  Particular  attention  should  be  given  to  the  absolute 
removal  of  all  manure,  the  smallest  particles  of  which  may  harbor 
innumerable  tuberculosis  germs. 

3.  Retest  the  herd  in  two  or  three  months  by  applying  the  ophthal- 
mic method  at  least  twice  and  immediately  remove  all  reactors  and 
again  clean  and  disinfect.  Every  six  months  apply  either  the  intra- 
dermal or  subcutaneous  test.  In  such  semi-annual  testing  we  prefer 
to  alternate  the  subcutaneous  and  intradermal  methods. 


4  Literature  describing  the  methods  of  stable  disinfection  may  be  obtained 
free  from  the  College  of  Agriculture,  University  of  California,  Berkeley,  California. 


16 

4.  Additions  to  the  herd  should  be  subjected  to  the  tuberculin  test 
and,  in  addition,  should  come  from  herds  that  are  comparatively  free 
from  reactors.  The  purchase  of  cattle  from  badly  infected  herds,  even 
when  they  pass  the  tuberculin  test,  is  unsatisfactory.  When  pur- 
chasing cattle  it  is  usually  impossible  to  find  any  for  sale  from  herds 
known  to  be  free  from  tuberculosis,  but  in  several  dairies  under  the 
supervision  of  this  station  it  has  been  found  entirely  practicable  to 
follow  the  rule  of  purchasing  only  from  herds  having  less  than  10 
per  cent  of  reactors.  Since  the  adoption  of  this  10  per  cent  rule  the 
proportion  of  reactors  at  each  semi-annual  test  has  been  much  less. 
Owners  of  herds  that  are  comparatively  free  from  tuberculosis  should 
make  few  purchases,  but  depend  on  the  raising  of  the  calves.  There 
is  great  danger  in  buying  non-reacting  cattle  from  infected  herds — 
that  is,  animals  that  have  been  exposed  to  infection.  The  unit  to  deal 
with  in  buying  cattle  is  the  sound  herd  rather  than  the  non-reacting 
individual  animal. 

In  the  dairies  near  cities,  where  it  is  not  economical  to  raise  the 
calves  and  the  milking  herd  is  kept  up  by  the  constant  purchase  of 
"springers,"  or  fresh  cows,  it  will  be  impossible  to  keep  the  herd  free 
from  reactors,  although  in  certain  dairies  of  this  class  the  number  of 
reactors  is  kept  down  to  an  average  of  about  3  per  cent  by  semi-annual 
testing  and  the  prompt  removal  of  reactors. 

The  Suppression  of  Tuberculosis  in  Moderately  Infected  Herds. 
In  herds  having  from  15  to  50  per  cent  of  reactors  the  best  course  to 
pursue  is  not  as  definitely  known  as  in  badly  infected  herds,  where  it 
is  hopeless  to  try  to  separate  the  infected  from  the  healthy  and  where 
dependence  must  be  placed  entirely  in  the  raising  of  healthy  young 
stock;  or  in  slightly  infected  herds,  where  it  is  always  advisable  to 
stamp  out  the  disease  by  repeated  tuberculin  tests  and  the  prompt 
removal  of  all  reactors.  In  moderately  infected  herds  there  are  many 
healthy  cattle  which  can  be  saved  from  infection  and  it  is  undesirable 
to  leave  them  with  the  infected  herd,  while,  on  the  other  hand,  the 
economic  sacrifice  entailed  in  the  sale  of  all  reacting  cattle  often  would 
be  a  far  greater  loss  than  any  that  would  be  caused  by  the  disease 
itself. 

The  so-called  Bang  System  is  sometimes  advisable.  The  method 
is  as  follows : 

1.  Test  every  animal  in  the  herd  with  tuberculin. 

2.  Remove  the  reacting  animals  and  keep  them  isolated  so  that  the 
disease  cannot  be  transmitted  to  the  healthy  animals  either  by  contact, 
by  the  attendants,  or  by  the  same  feeding  or  drinking  utensils. 


17 

3.  Clean,  disinfect  and  paint  or  whitewash  the  stable  to  prevent 
transmission  of  the  germs  left  by  the  infected  animals. 

4.  Test  the  healthy  herd  with  tuberculin  regularly  to  detect  any 
cases  that  may  develop  and  remove  such  animals  before  they  spread 
the  disease.    Disinfect  again. 

5.  Remove  the  calves  from  the  diseased  herd  at  birth  and  feed 
them  milk  from  the  healthy  cows  or  milk  from  the  diseased  cows  after 
thorough  pasteurization  by  heating  to  160  °  F.  for  20  minutes. 

As  the  sound  herd  is  replenished,  the  isolated  cattle  may,  if  de- 
sired, be  fattened  and  killed  for  beef  under  proper  inspection.  When 
new  or  non-infected  buildings  and  corrals  and  well  separated  pastures 
are  available  for  housing  the  non-reacting  cattle  this  Bang  System 
or  some  of  its  modifications  may  be  attempted.  Through  the  failure 
to  guard  against  the  limitations  of  the  tuberculin  test  by  repeated  re- 
testing,  or  through  inadequate  separation  of  the  two  herds,  many, 
after  trying  this  system  for  years,  have  failed  to  make  headway  in 
building  up  a  healthy  herd.  In  many  instances  it  will  be  cheaper  for 
dairymen  in  whose  herds  over  35  per  cent  of  the  animals  react  to  keep 
the  entire  adult  herd  as  one  unit  and  for  a  time  devote  all  efforts  to 
protecting  the  new-born  calves.  In  such  cases  a  frequent  physical 
examination  of  the  infected  herd  is  desirable  in  order  to  eliminate 
clinical  cases  as  soon  as  possible  after  they  develop. 

In  herds  having  less  than  35  per  cent  reactors  it  may  sometimes 
be  desirable  to  try  to  stamp  out  the  disease  by  repeated  tuberculin 
testing  and  the  prompt  removal  of  all  reactors,  each  test  being  fol- 
lowed by  a  thorough  cleaning  and  disinfecting  of  the  premises.  The 
tuberculin  tests  must  be  interpreted  very  rigidly  and  all  questionable 
reactions  treated  as  if  they  were  positive ;  otherwise  the  procedure  will 
often  fail  to  stop  the  headway  of  the  disease  until  so  many  animals 
have  been  changed  by  repeated  tests  and  additions  that  the  majority 
of  the  animals  have  been  substituted. 

In  badly  infected  herds  one  should  proceed  as  if  every  animal  were 
infected.  In  herds  having  over  50  per  cent  of  reactors  all  of  the 
mature  cattle  should  be  treated  as  if  infected.  The  tuberculin  test  is 
of  value  in  indicating  that  a  severe  infection  exists,  but  not  of  value 
in  such  herds  as  a  means  of  dividing  the  non-infected  from  the  tuber- 
culous. To  control  the  disease  dependence  must  be  placed  upon  the 
following  procedure : 

1.  Eliminate  promptly  all  animals  developing  physical  signs  of 
the  disease. 

2.  Remove  all  calves  at  birth  and  raise  them  on  boiled  or  pasteur- 
ized milk. 


18 

3.  Keep  all  healthy  young  stock  isolated  from  the  infected  herd, 
infected  fields  and  water.  Test  them  every  six  months  by  the  intra- 
dermal method  and  remove  any  reactors.5 

Calves  are  so  seldom  born  tuberculous  that  such  means  of  trans- 
mission may  be  ignored ;  hence,  if  all  calves  were  kept  free  from  the 
disease  it  would  require  only  one  generation  of  cattle  to  eradicate 
tuberculosis.  In  carrying  this  principle  into  effect  the  ideal  way 
would  be  to  build  up  a  separate  herd  from  the  healthy  young  stock. 
This,  however,  is  not  always  practicable.  When  it  is  necessary  to 
add  the  healthy  young  stock  to  the  infected  herd  all  of  the  cattle 
should  be  given  careful  and  frequent  physical  examinations  by  a 
veterinarian  to  eliminate  the  open  cases  as  far  as  possible.  This  pro- 
cedure of  protecting  the  calves  and  young  stock  and  of  keeping  down 
the  proportion  of  open  cases  by  frequent  physical  examinations  is 
called  Ostertag's  System,  named  after  its  chief  advocate,  Dr.  Robert 
Ostertag  of  Berlin,  Germany.  This  system  is  a  process  of  gradually 
weeding  out  and  reducing  the  disease  rather  than  a  process  of  com- 
plete eradication. 

THE  IMPORTANCE  OF  SEGREGATION  AND  ISOLATION 

In  large  herds  it  is  advisable  to  keep  the  cattle  in  small  units.  In 
constructing  buildings  and  corrals,  plan  at  the  least  to  have  separate 
corrals  for  each  group  of  fifty  or  sixty  cattle.  Provide  separate  water 
troughs  for  each  corral.  Train  the  cows  to  stand  always  in  the  same 
stanchion.  Do  not  feed  the  calves  with  the  sweepings  from  the  feed 
troughs  in  the  dairy  barn  and  do  not  permit  hogs  or  goats  in  the  cattle 
corrals. 

SUGGESTIONS  REGARDING  SANITATION 

Construct  water  troughs  so  that  the  drinking  water  of  the  cattle 
does  not  become  contaminated  with  manure.  Do  not  allow  the  cattle 
access  to  ponds  or  water  holes.  Have  plenty  of  windows  to  admit  an 
abundance  of  sunlight  to  all  buildings.  Direct  sunlight  is  more  deadly 
to  fully  exposed  tubercle  bacilli  than  carbolic  acid,  cresol,  corrosive 
sublimate  or  chloride  of  lime  in  the  dilutions  generally  used  in  dis- 
infecting. 

One  would  suppose  that  tight  barns  would  be  unnecessary  in  Cali- 
fornia, where  the  cows  can  live  out  of  doors  for  a  greater  length  of 
time  than  in  the  eastern  states,  but  it  must  be  admitted  that  the  climate 


s  Even  when  the  non-reacting  cattle  are  at  once  removed  from  a  herd  having 
over  50  per  cent  reactors  they  should  be  looked  upon  as  suspicious  until  some 
time  has  elapsed  and  they  have  successfully  passed  repeated  tuberculin  tests. 
The  repeated  use  of  the  ophthalmic  test  is  useful  in  such  cases. 


19 

of  the  coast  counties  requires  warm  shelter  for  high-grade  dairy  cows. 
Ventilation  is  a  sanitary  factor  which  in  some  instances  has  been  neg- 
lected. This  should  be  provided  not  only  in  milking  stables  but  also 
in  the  barns  used  exclusively  for  shelter  and  feeding. 

HOW  CLEANLINESS  HELPS 

The  desirability  of  cleanliness  in  milking,  cooling  and  transporting 
milk  is  realized  by  all.  Few,  however,  realize  the  significance  of 
cleanliness  is  a  factor  influencing  the  health  of  the  cattle.  Since  the 
manure  of  tuberculous  cattle  often  contains  living  tubercle  bacilli  in 
vast  numbers,  the  importance  of  keeping  it  well  cleaned  out  of  the 
stable  and  corrals  is  readily  seen. 

Stables  should  be  cleaned  out  regularly  and  the  manure  put  where 
it  cannot  be  picked  over  by  hogs  or  cattle.  These  animals  are  easily 
infected  in  that  way.  Cleanliness  also  includes  keeping  the  walls  and 
ceilings  free  from  dirt,  dust  and  cobwebs.  These  are  all  good  resting 
places  for  disease  germs. 

Whitewashing  the  interior  of  the  stable  at  least  twice  a  year  is  a 
great  aid  to  cleanliness  and  also  has  a  distinct  effect  in  destrojdng 
disease  germs,  especially  when  applied  after  thorough  cleaning.  In 
many  municipalities  dairy  stables  are  required  to  be  whitewashed  at 
regular  intervals.    This  should  be  a  universal  practice. 


STATION  PUBLICATIONS  AVAILABLE  FOE  DISTRIBUTION 


REPORTS 

1897.      Resistant  Vines,   their   Selection,  Adaptation,   and  Grafting.     Appendix  to  Viticultural 
Report  for   1896. 

1902.  Report  of  the  Agricultural  Experiment  Station  for  1898-1901. 

1903.  Report  of  the  Agricultural  Experiment  Station  for   1901-03. 

1904.  Twenty-second  Report  of  the  Agricultural  Experiment  Station  for  1903-04. 

1914.  Report  of  the  College  of  Agriculture  and  the  Agricultural   Experiment   Station,   July, 

1913-June,   1914. 

1915.  Report  of  the  College  of  Agriculture  and  the  Agricultural  Experiment   Station,    Julv, 

1914-June,   1915. 


No. 
168. 

169. 
178. 
184. 

185. 

195. 

207. 
208. 
212. 
213. 
216. 


225. 
227. 
230. 
234. 
241. 
242. 
246. 
248. 

249. 

250. 


Observations  on  Some  Vine  Diseases 
in   Sonoma  County. 

Tolerance  of  the  Sugar  Beet  for  Alkali. 

Mosquito  Control. 

Report  of  the  Plant  Pathologist  to 
July   1,    1906. 

Report  of  Progress  in  Cereal  Investi- 
gations. 

The   California   Grape  Root-worm. 

The  Control  of  the  Argentine  Ant. 

The  Late  Blight  of  Celery. 

California  White  Wheats. 

The  Principles  of  Wine-making. 

A  Progress  Report  Upon  Soil  and  Cli- 
matic Factors  Influencing  the  Com- 
position of  Wheat. 

Tolerance  of  Eucalyptus  for  Alkali. 

Grape  Vinegar. 

Enological  Investigations. 

Red  Sniders  and  Mites  of  Citrus  Trees. 

Vine  Pruning  in  California,  Part  I. 

Humus  in  California   Soils. 

Vine   Pruning  in   California,    Part  II. 

The  Economic  Value  of  Pacific  Coast 
Kelps. 

Stock-Poisoning  Plants  of  California. 

The  Loquat. 


BULLETINS 
No. 
251. 


252. 
253. 

254. 
255. 
256. 
257. 
261. 

262. 

263. 
265. 
266. 

267. 
268. 
269. 
270. 


271. 


Utilization  of  the  Nitrogen  and  Organic 
Matter  in  Septic  and  Imhoff  Tank 
Sludges. 

Deterioration  of  Lumber. 

Irrigation  and  Soil  Conditions  in  the 
Sierra   Nevada   Foothills,    California. 

The  Avocado  in  California. 

The  Citricola  Scale. 

Value  of  Barley  for  Cows  Fed  Alfalfa. 

New  Dosage  Tables. 

Melaxuma  of  the  Walnut,  "Juglans 
regia." 

Citrus  Diseases  of  Florida  and  Cuba 
Compared  with  Those  of  California. 

Size  Grade  for  Ripe  Olives. 

Cottony  Rot  of  Lemons  in  California. 

A  Spotting  of  Citrus  Fruits  Due  to  the 
Action  of  Oil  Liberated  from  the  Rind. 

Experiments  with  Stocks  for  Citrus. 

Growing  and  Grafting  Olive  Seedlings. 

Phenolic   Insecticides   and  Fungicides. 

A  Comparison  of  Annual  Cropping, 
Biennial  Cropping,  and  Green  Ma- 
nures on  the  Yield  of  Wheat. 

Feeding  Dairy  Calves  in  California. 


No. 

65.   The  California   Insecticide  Law. 

69.  The   Extermination    of    Morning-Glory. 

70.  Observations    on    the    Status    of    Corn 

Growing  in   California. 
76.   Hot   Room   Callusing. 
82.   The     Common     Ground     Squirrels     of 

California. 

106.  Directions  for  Using  Anti-Hog  Cholera 

Serum. 

107.  Spraying  Walnut  Trees  for  Blight  and 

Aphis    Control. 

108.  Grape  Juice. 

109.  Communit-   or   Local   Extension   Work 

by  the  High  School  Agricultural  De- 
partment. 

113.  Correspondence  Courses  in  Agriculture. 

114.  Increasing  the  Duty  of  Water. 

115.  Grafting  Vinifera  Vineyards. 

117.  The    Selection    and    Cost    of    a    Small 

Pumping  Plant. 

118.  The  County  Farm  Bureau. 

121.    Some    Things    the    Prospective    Settler 

Should  Know. 
124.   Alfalfa   Silage  for  Fattening  Steers. 

126.  Spraying  for  the  Grape  Leaf  Hopper. 

127.  House  Fumigation. 

128.  Insecticide  Formulas. 

129.  The  Control  of  Citrus  Insects. 

130.  Cabbage   Growing  in   California. 

131.  Spraying  for  Control  of  Walnut  Aphis. 

132.  When      to      Vaccinate      against      Hog 

Cholera. 

133.  County  Farm  Adviser. 

134.  Control  of  Raisin   Insects. 


CIRCULARS 
No. 


135.  Official  Tests  of  Dairy  Cows. 

136.  Melilotus   Indica. 

137.  Wood  Decay  in  Orchard  Trees. 

138.  The  Silo  in  California  Agriculture. 

139.  The   Generation   of   Hydrocyanic   Acid 

Gas  in  Fumigation  by  Portable  Ma- 
chines. 

The  Practical  Application  of  Improved 
Methods  of  Fermentation  in  Califor- 
nia Wineries  during  1913  and  1914. 

Standard  Insecticides  and  Fungicides 
versus   Secret  Preparations. 

Practical  and  Inexpensive  Poultry  Ap- 
pliances. 

Control  of  Grasshoppers  in  Imperial 
Valley. 

Oidium  or  Powdery  Mildew  of  the  Vine. 

145.  Suggestions  to  Poultrymen  concerning 

Chicken  Pox. 

146.  Jellies    and    Marmalades    from    Citrus 

Fruits. 

147.  Tomato  Growing  in  California. 

148.  "Lungworms." 
Lawn  Making  in  California 
Round  Worms  in  Poultry. 
Feeding  and  Management  of  Hogs. 
Some  Observations  on  the  Bulk  Hand- 
ling of  Grain  in  California. 

Announcement  of  the  California  State 

Dairy  Cow  Competition,  1916-18. 
Irrigation   Practice  in   Growing  Small 
Fruits  in  California. 
155.   Bovine  Tuberculosis. 


140. 


141. 


142. 
143. 


144. 


149. 
150. 
151. 
152. 

153. 

154. 


